Roller-type dressers for grinding wheels



Dec. 11, 1962 H. E. BALSIGER 3,067,732

ROLLER-TYPE DRESSERS FOR GRINDING WHEELS Filed Oct. 29, 1958 6Sheets-Sheet 1 LL INVENTOR l HARULD E-BALSIGER BY l Z )1 TTORNEY Dec.11, 1962 E. BALSIGER 3,067,732

ROLLER-TYPE DRESSERS FOR GRINDING WHEELS Filed (kit. 29, 1958 6Sheets-Sheet 2 INVENTOR- HAROLD EEALSIGER BYgkM ATTORNE/IY Dec. 11, 1962H. E. BALSIGER ROLLER-TYPE DRESSERS FOR GRINDING WHEELS 6 Sheets-Sheet 3Filed Oct. 29, 1958 INVENTOR HAROLD E.BALSI6ER TTORNEY 1962 H. E.BALSIGER 3,067,732

ROLLER-TYPE DRESSERS FOR GRINDING WHEELS Filed Oct. 29, 1958 6Sheets-Sheet 4 TRAVERSE PATH OFROLLER PERIPHERAL SPEED OF GRINDING WHEELDRESSING .S'PEZD INVENTOR HAROLD LBALSIGER ATTORNEY Dec. 11, 1962 H. E.BALSIGER 3, 67,

ROLLER-TYPE DRESSERS FOR GRINDING WHEELS Filed Oct. 29, 1958 6Sheets-Sheet 5 INVENTOR HAROLD anus/can BY/KbM ATTORNEY Dec. 11, 1962 H.E. BALSIGER 3,067,732

ROLLER-TYPE DRESSERS FOR GRINDING WHEELS Filed Oct. 29, 1958- 6Sheets-Sheet 6 lNVENTOR HAROLD E BALS/GER BY/gxmj TTORNEY United States3,067,732 Patented Dec. 11, 1962 v 3,067,732 I *RGLLER-TYPE DRESSERS FQRGRINDING WHEELS Harold E. Balsiger, Wayneshoro, Pa, assignor to LandisTool Company, Waynesboro, Pa.

Filed @et. 29, 1958, Ser. No. 770,404 9 Claims. (Cl. 125-11) Thisinvention relates to apparatus for dressing the operative surfaces ofabrasive wheels.

Over a period of years, two types of wheel dressing apparatus have beenin general use for dressing abrasive wheel surfaces. By far, the mostwidely used is the single point diamond which is generally mounted in asuitable holder which, in turn, is supported on a sliding member so thatthe diamond may be traversed slowly in contact with theoperative face ofthe abrasive wheel.

A great deal of heat is generated in the diamond of a single diamonddresser during a dressing operation and this causes the diamond to wearmore rapidly. Finally, diamond wear has become a greater factor inquality control because of the increasingly finer limits of size andtaper demanded by machine users. One pass of a single diamond across agrinding wheel may cause sufficient wear on the diamond to dress a tapergreater than tolerance permits. Another disadvantage of a non-rotatablediamond is that it tends to press the metal particles into the wheel andmust remove a greater amount of abrasive in order to remove all themetal.

The second type of dressing apparatus, in use to a lesser extent is theabrasive wheel or roller which may have 'a mounting similar to that ofthe diamond dresser. These abrasive rollers are rotatably mounted sothat when they engage a grinding wheel, they are rotated at a relativelyhigh speed. Provision is made in the form of a braking device to causethe roller to travel at a lesser surface speed than that of the grindingwheel and thus provide a relative movement between the two surfaces toeffect the dressing action. It is recommended by the producers of thesewheels, that in order to obtain a fine finish on the grinding wheel,they should be mounted with the aXis parallel to that of the grindingwheel. If a coarse surface is desired on the wheel, the roller should beset at an angle of not more than 30.

Wheels and rollers having operative surfaces consisting of diamondparticles instead of synthetic abrasive grains, have been used forgrinding and also for dressing grinding wheels. When used for dressing agrinding wheel, the axis of the dressing wheel or roller is parallel tothe axis of :the :grinding wheel. The dressing roller must rotate at adifferent surface speed from that of the grinding wheel and, therefore,it must either have a separate driving means or if dependent on therotation of the grinding wheel, it must have some sort of a brakingdevice.

It has been discovered that a diamond impregnated roller or a rollerhaving diamonds or other hard-substances set therein or a carbide rollermounted at an angle greater than 30 and preferably about 45 to thegrinding wheel, freely rotatable and slidably supported on a suitablecarriagefor traversing across the face of a grinding wheel, is a decidedimprovement over the devices described above. It can dress a wheel withfewer passes than a single point diamond and with no measurable wear.per pass. Since each diamond is only in contact with the grinding wheelfor a short period of time, there is practically no heat generated andthe life of the individual diamond is correspondingly increased. Becauseof the angular setting of the roller, the roller is driven by the wheelat a speed in proportion to the angle and thus neither a braking devicenor a separate driving device is necessary. The long wearing quality ofthis type of dressing device provides additional beneficial results, inthat, wear of the dressing tool is not rapid enough to cause taper.Because of the angular relation between the roller and wheel, metalwhich has become embedded in the grinding wheel, is removed much moreeffectively than with a single or multiple traversing diamonds.

The roller type dressing tool described herein may also be used forprofile dressing on the face and corners of a grinding wheel. This maybe accomplished by using a profile bar with a follower havingsubstantially the same diameter as the dressing roller.

It is an object of this invention to provide a dressing tool which willmaintain a constant diameter across the peripheral face of the grindingwheel.

A further object is to provide a dressing tool in the form of a rollercomposedof solid materials or embedded particles of a hardness of 9 ormore on the Mob scale.

A further object is to provide a dressing roller having embedded thereincutting particles of a size such that they number less than 50 particlesper carat.

A further object is to provide a dressing roller rotatably mounted forrotation by engagement with a rotating grinding wheel, the rate ofrotation being determined only by the angular relation between thedressing roller and the grinding wheel.

A further object is to provide a rotatable dressing device having -aplurality of diamonds, each of which engages the wheel only momentarilyin a direction inclined to the direction of rotation of the grindingwheel.

A further object is to provide means for initiating the rotation of thedressing roller before it engages the :grinding wheel.

A further object is to provide means for guiding said dressing rolleraround the corners of a grinding wheel.

A further object is to provide an adjustable profile bar for guidingsaid dressing roller which may be adjusted to compensate for reductionin diameter of the roller due to wear.

A further object is to provide a dressing device which will effect animproved dressing operation with a reduced change in wheel diameter perdressing.

A further object is to provide means whereby each diamond on the rollereffects a digging action on the wheel rather than a mere passageacrossthe face of the wheel. This action has the effect of removing metalcuttings from the wheel with less reduction in the diameter of the wheelthan is caused by the use of conventional non-rotatable diamonddressers. Because of the minimum reduction in diameter of the wheel, thewheel dressed by this device lasts as much as 30% longer than wheelsdressed by conventional dressing tools.

The preferred embodiment ofthe invention has been illustrated by way ofexample on the accompanying drawings in which- FIGURE '1 is 'a frontelevation partly in section of a roller-type dresser showing the profilebar and follower, and the motor for traversing the dresser across agrinding wheel.

FIGURE 2 is an enlarged end elevation of the dressing tool showing itsinclined relation to the grinding wheel.

FIGURE 3 is .a transverse vertical section on the 'line 33 of FIGURE 2.

FIGURE 4 is an enlarged front elevation of the .adjustable profile barand follower.

FIGURE 5 is arr-enlarged end elevation of the adjustable pro-file barand follower.

FIGURE 6 is a diagram showing the path of travel of individualdiamondparticles across the face of the grinding wheel.

FIGURE 7 is a partial end elevation of a double disc grinder with onedisc broken away to show a roller-type dresser adapted for dressing theopposing abrasive discs.

FIGURE 8 is a transverse section on the line S8 of FIGURE 7 and FIGURE 9is a sectional end elevation of the dresser feed mechanism.

Numeral 10 indicates a support member on a grinding machine forsupporting a dressing device. A cylinder 11 attached to support member10 has a sleeve or liner 12 in which a piston 13 is slidably mounted.Dresser carriage 14 is slidably supported on member 10. Piston rod 15,extending from the left end of cylinder 11, is attached to dressercarriage 14 by means of lug 16 on said carriage.

A dressing tool mounted for vertical adjustment in dresser carriage 14consists of a cylindrical guide member 20 in which is slidably mounted atool holder 21, at the lower end of which is attached an angularlyadjustable member 22'. A dressing roller 22 is rotatably mounted inmember 22' for rotation in a plane or direction of rotation about 45inclined to the plane or y direction of rotation of grinding wheel 23.The means for eifecting said vertical adjustment consists of a screw 24inserted into a pair of axially spaced nuts 25 and 26 in tool holder 21.A spring 27 between said nuts 25 and 26, serves as a means for taking upbacklash. Knob 28 resting on the top of screw 24 provides means foreffecting manual adjustment of roller 22 toward and from grinding wheel23.

While the primary purpose of dresser roller 22 is the dressing of astraight grinding surface on a grinding wheel, formed surfaces may bedressed by using roller 22 in combination with a profile bar. A profilebar consisting of members and 36 substantially identical in shape, aremounted side by side for relative adjustment longitudinally of oneanother and are mounted in bracket 37 attached to a suitable stationarypart of the dresser mounting 11. The relative adjustment of members 35and 36 is effected by means of adjusting screws 46 for member 35 andadjusting screws 41 for member 36.

Guide piston 42 in cylinder 43 is urged downwardly by means of spring44. Piston 42 has a piston rod 45 which is connected in a suitablemanner to the upper end of tool holder 21. Follower roller 46 isrotatably mounted in bracket 47. Bracket 47 is attached to piston rod 45by means of screws 48 and 49. Spring 44 serves to maintain operativeengagement between roller 46 and profile members 35 and 36 so as toeffect a precise movement of roller 22 relative to grinding wheel 23. Ifnecessary, bracket 47 and roller 46 may be positioned angularly relativeto the profile members 35 and 36 to correspond to the position of roller22 relative to grinding wheel 23. However, the advantage of such anarrangement is so slight as to be practically negligible except in casesrequiring unusual precision.

The primary purpose of this adjustment is to compensate for change inthe diameter of roller 22. As roller 22 wears, members 35 and 36 areextended equally in opposite directions so as to increase the length ofthe profile bar by an amount corresponding to, but not necessarily equalto the wear of roller 22.

Roller 22 is in the form of a ring having a plurality of diamond Orother hard particles'mounted in the peripheral surface thereof and isattached to cylindrical member 60 having a large diameter end 61 and asmall diameter end 62. When roller 22 is used for the purpose ofdressing the corners as well as the face of the wheel 23, it may bedesirable to extend the operative surface to include a radius on eachcorner of said roller 22 with cutting particles distributed over theradius the same as on the face of roller 22.

The size of the diamond particles is such that they number aboutparticles or less per carat. Roller 22 is mounted on the small diameterend 62 and held against the shoulder at the junction of said smalldiameter end 21. and said large diameter end by means of collar 63 andnut 64.

Cylindrical member 60 is rotatably mounted on a stationary shaft 70 heldagainst rotation at the left end of bracket 71 by means of screw 72 andcap 72, and at the right end of said bracket 71 by cap 73 and screws 74.Member 60 is rotatably supported on anti-friction bearings '75 and 76.The outer rings of said bearings are held in spaced relation by sleeve80. The inner rings of said bearings are held in spaced relation underload by a member consisting of a spool 81 mounted on shaft 70 and havingflanged portions 82. Between spool 81 and each of said inner bearingrings is a resilient member 83 also mounted on shaft 70 and having a hubportion extending axially outwardly to engage the inner rings and a rimportion extending inwardly to engage the flanged portions 82 of spool81.

An axial bore in shaft 71 is connected through a radial bore 91 throughgroove 92 with the outer surface of shaft 70 in alignment with aplurality of radial openings 93 and spool 81. Bore 9G is also connectedthrough radial passages 1th? in the left end of shaft 70 which areconnected through radial bores 101 in ring 102 through a plurality ofnon-radial outlets 103 in member 60. Ring 102 is pressed into member 60and is preferably of softer material than shaft 70 or member 60.

Air and oil mist is introduced under pressure in bore 90 and isdistributed through bores 101 and openings 93 in spool 81 to providelubricant for bearings 75 and 76. This air and oil mist produces anoutward pressure on said bearings to prevent the entry of water or dirtinto said bearings. The air under pressure is also directed from bore 90through passages and outlets 103 to provide a preliminary rotation ofmember 60 and roller 22.

Roller 22 may be attached to tool holder 21 in a fixed position forrotation in a direction at an inclination to the direction of rotationof the wheel. It may also be mounted for angular adjustment if suchadjustment is required or if it appears to be desirable. The preferredangle of roller 22 relative to wheel 23 is approximately 45. Asindicated above, preliminary rotation of roller 22 is effected beforeroller 22 engages wheel 23.

Thereafter, the action of wheel 23 on roller 22 will continue therotation of roller 22 at a surface speed approximately half of that ofwheel 23 for a 45 setting. It must be remembered that roller 22 ismounted for free rotation on shaft 70, and its rate of rotation isdependent entirely upon the surface speed of wheel 23 modified by theangular relation between roller 22 and wheel 23.

FIGURE 6 shows the direction of cut of one of the diamonds in roller 22on wheel 23. The speed of wheel 23 is indicated by line A. The speed ofroller 22 is indicated by line B. Assuming that the diamond X has justengaged the peripheral surface of wheel 23, the point of contact of thediamond with the wheel moves in the direction of line A while thediamond moves in the direction of line B. During this time, roller 22itself has moved in a horizontal direction to the end of line B. Whilethe point on the wheel travels the distance indicated by line A, thediamond is travelling the distance indicated by line B. The resultantpath or cut of the diamond on wheel 23 is in the direction of line C.The resultant path on wheel 23 of a particular point on roller 22 isline C joining lines A and B. This lines is substantially parallel tothe axis of roller 22. The path of each of the other diamonds of roller22 on wheel 23 is in the same direction and of the same length as thatof diamond X. Each diamond is thus in contact with wheel 23 for a veryshort period at a time, so that very little heat is generated in anyindividual diamond.

Because the dressing operation is distributed over a plurality ofdiamonds, the diamond wear is correspondingly distributed with theresult that roller 22 crosses the face of wheel 23 and there is no wearwhich would result in a variation in diameter of wheel 23 from one 'endto the other. This represents a decided improvement over non-rotatingdressers, one of the greatest faults of which is the dressing of a taperon Wheel 23 due to the wear of the diamond as it passes across theoperative face of said wheel. An example of an application of this typeof dresser would include a grinding whe'el having a peripheral surfacespeed of 8000 feet per minute. A dressing roller set to rotate at anangle of 45 to the direction of rotation of the wheel will be driven bythe wheel at a surface speed of approximately 4000 feet per minute.

The resulting effect produced by all the diamonds in roller 22 on wheel23, is a plurality of lines such as line C. Thus, the peripheral lineswhich are the usual effect of single or multiple diamond fixed tools andwhich often produce a corresponding pattern on the surface of aworkpiece, are completely eliminated by providing a dressing tool whichmakes a pltu'ality of short cuts inclined to the direction of rotationof the wheel rather than continuous cuts parallel with the direction ofthe wheel.

The principal effect of this type of dresser on a grinding wheel is thatdressing is performed by a plurality of diamonds, each taking arelatively small cut so that the wear on each diamond is so slight as tobe negligible. The result of this arrangement is that as the dressingroller passes across a grinding wheel, wear on the diamonds is sodistributed that at the end of a pass of the dressing roller across thewheel, the wheel is the same diameter at both ends and, therefore, willgrind a work surface of constant diameter rather than a taper.

Another effect of this type of dresser on a grinding wheel is that eachdiamond, as it rotates on the roller, enters the surface of the grindingwheel, penetrating to a depth depending upon the radius of the rollerand then rotates out of contact with the wheel. This action of thediamond is more effective in removing metal particles from the abrasivesurface than the conventional dressing tool, and thus requires fewerpasses of the dressing roller and less reduction in wheel diameter foreach dressing operation.

In FIGURES 7 and 8, the spaced grinding discs 120 and 121 are dressed bymovement of a dressing arm 125 between said discs. Arm 125 may bepivotally mounted as shown in the drawings in which apneumatic-hydraulic device 126 is anchored in frame 127 and attached toarm 125 through link 128. It may be mounted for sliding movement asshown, for example, in US. Patent application Serial No. 742,595, filedJune 17, 1958 issued as Patent No. 3,018,589, dated January 30, 1962.

Regardless of whether arm 125 is pivotally or slida'bly mounted, itcarries at one end a pair of oppositely positioned rollers 130substantially identical with roller 22 of FIGURES 2 and 3. Rollers 130are angularly positioned in arm 125 so as to rotate in a direction at anangle of approximately 45 to their path of travel across discs 120 and121. Here again, the effect of negligible wear of the diamonds plus theabsence of peripheral or annular diamond lines on the discs, make for asub stantial improvement in the quality of work produced on a machineequipped with this type of dresser.

The invention as described and illustrated above by way of example iscapable of minor change in arrangement and material without departingfrom the scope as defined in the following claims.

I claim:

1. In a grinding machine, a rotatably mounted grinding wheel, a dressingtool, means for effecting a relative transverse and axial movementbetween said dressng tool and said grinding wheel, said dressing toolcomprising a diamond dressing roller mounted for free rotation in anoblique direction inclined more than 45 degrees to the direction ofrotation of said grinding wheel whereby said roller is driven by saidgrinding wheel at a surface speed substantially different than that ofthe grinding wheel and means for dressing a predetermined form on saidgrinding wheel comprising a fixed forming bar, a follower connected tosaid roller and mounted for operative engagement with said forming bar,the portion of said follower engaging the forming bar beingsubstantially the same shape and diameter as the dressing roller.

2. In a grinding machine, a rotatably mounted grinding wheel, a dressingtool, means for effecting a relative transverse and axial movementbetween said dressing tool and said grinding wheel, said dressing toolcomprising a roller mounted for free rotation in an oblique directioninclined more than 45 degrees to the direction of rotation of saidgrinding wheel whereby said roller is driven by said grinding wheel at asurface speed substantially different than that of the grinding wheeland means for dressing a predetermined form on said grinding wheelcomprising a fixed forming bar, a follower connected to said roller andmounted for operative engagement with said forming bar, the portion ofsaid follower engaging the forming bar being substantially the sameshape and diameter as the dressing roller, said forming bar consistingof a pair of profile members longitudinally adjustable relative to oneanother to compensate for Wear on said dressing roller.

-3. In a dressing devicefor a rotatable grinding wheel, a dressing tool,supporting means for said dressing tool, means for effecting a relativetransverse movement between said supporting means and the operativesurface of said grinding wheel, said dressing tool comprising a holdermounted in said supporting means, a diamond dressing roller rotatablymounted for free rotation in said holder, power means for effecting apreliminary rotation of said roller before it engages the grindingwheel, said roller being driven by said grinding wheel after saidengagement, the relation between said roller and said grinding wheelbeing such that the surface speed of said roller is approximately halfthe surface speed of said grinding wheel.

4. In a dressing device for a rotatable grinding wheel, a dressing tool,supporting means for said dressing tool, means for effecting a relativetransverse movement between said supporting means and the operativesurface of said grinding wheel, said dressing tool comprising a holdermounted in said supporting means, a diamond dressing roller rotatablymounted for free rotation in said holder, said roller being positionedso as to rotate at an angle to the direction of rotation of saidgrinding wheel, and power means for effecting a preliminary rotation ofsaid roller before it engages said grinding wheel.

5. In a dressing device for a rotatable grinding Wheel, a diamonddressing tool, supporting means for said dressing tool, means foreffecting a relative transverse movement between said supporting meansand the operative surface of said grinding wheel, said dressing toolcomprsing a holder mounted in said supporting means, a dressing rollerrotatably mounted for free rotation in said holder, a supply of fluidunder pressure, and means on said roller co-acting with said fluid underpressure to cause a preliminary rotation of said roller prior toengagement of the roller and the grinding wheel.

6 In a dressing device for a rotatable grinding wheel, a dressing tool,supporting means for said dressing tool, means for effecting a relativetransverse movement between said supporting means and the operativesurface of said grinding wheel, said dressing tool comprising a holdermounted in said supporting means, a dressing roller rotatably mountedfor free rotation in said holder, means for effecting a preliminaryrotation of said roller before it engages the grinding wheel, a supplyof fluid under pressure, passages for said fluid through said roller anddischarge openings connected to said passages and peripherally spaced insaid roller for effecting rotation of said roller in response to passageof said fluid through said discharge openings.

7. In a dressing device for a rotatable grinding wheel, a dressing tool,supporting means for said dressing tool, means for effecting 'a relativetransverse movement between said supporting means and the operativesurface of said grinding wheel, said dressing tool comprising a holdermounted in said supporting means, a shaft in said holder, anti-frictionbearings axially spaced on said shaft, a dressing roller rotatablymounted for free rotation on said bearings, means for effecting apreliminary rotation of said roller before it engages the grindingWheel, comprising a supply of air under pressure mixed with a lubricant,passages through said roller for directing a portion of said air toprovide a pressure within said roller greater than the pressure outsidesaid roller and passages for directing another portion of said air toperipherally spaced points of discharge on said roller.

8. In a dressing device for a rotatable grinding wheel, a dressing tool,supporting means for said dressing tool, means for effecting a relativetransverse movement between said supporting means and the operativesurface of said grinding wheel, said dressing tool comprising a holdermounted in said supporting means, a diamond dressing roller rotatablymounted for free rotation in said holder, said roller comprising asupporting shaft, anti-friction bearings axially spaced on said shaft, asleeve rotatably supported on said bearings, a turbine drive meansco-acting with said sleeve, a collar on said sleeve, abrasive particlesdistributed about the peripheral surface of said collar, a supply offluid under pressure consisting of air and a lubricant in the form of amist,

8 and means for directing said fluid under pressure to a (point in saidsleeve whereby to lubricate said bearings to drive said turbine meansand to prevent undesirable elements from entering said bearings.

9. In a dressing device for a rotatable grinding wheel, a dressing tool,supporting means for said dressing tool, said dressing tool comprising aholder mounted in said supporting means, a dressing roller rotatablymounted for free rotation in said holder, means for effecting apreliminary rotation of said roller before it engages the grindingwheel, a supply of fluid under pressure, passages for said' fluidthrough said roller and discharge openings connected to said passagesand peripherally spaced in said roller for effecting rotation of saidroller in response to passage of said fluid through said dischargeopenings.

References Cited in the file of this patent UNITED STATES PATENTS1,687,252 Laessker Oct. 9, 1928 1,860,614 Hohnhorst May 31, 19322,135,202 Scrivener Nov. 1, 1938 2,380,451 Koebel July 31, 19452,528,621 Sweetser Nov. 7, 1950 2,809,474 Newman Oct. 15, 1957 2,861,561Olson Nov. 25, 1958 FOREIGN PATENTS 896,678 France Feb. 28, 1945

